Is Nearsightedness on the Rise?

Eye doctors seldom have a shortage of nearsighted patients to examine. Researchers have discovered a 17% increase in the prevalence of nearsightedness over the last 30 years. In the United States, nearsightedness affects 42% of the population. There also seems to be a huge surge of not only nearsighted eyes in certain Asian countries, such as Singapore, but very high amounts of nearsightedness developing at an early age.

Nearsightedness is now a public health concern.

Why is this happening? Children are growing up in a very different world today. Kids tend to spend more time indoors doing intense near work, playing video games and using various hand-held digital devices. Studies have found that children who spend more time outdoors are less likely to become nearsighted. Being nearsighted is not only a significant vision problem: it can also put one at risk for developing serious eye health conditions such as choroidal neovascularization, glaucoma, cataracts and retinal detachments.

Eye scientists are eager to study the development of nearsightedness. It was once thought smart to leave a child's nearsightedness alone, without correcting it. However, under-correcting one’s nearsightedness in some cases has shown to cause even more nearsightedness to develop. Scientists feel there is a central and a peripheral focusing or defocusing of the eye that causes it to elongate and make one more nearsighted.

Following are a few things that vision scientists are researching that may reduce the progression of nearsightedness.

Bifocals or Invisible No-line Progressive Lenses

Bifocal or progressive lenses are designed to correct basic vision problems by correcting both distance vision and near vision by adding a more “plus” or positive prescription to a patient’s distance prescription.

Bifocals are prescribed to people with an inability to focus on near objects and also for presbyopia, the common condition that happens to those of us over forty years of age in which the eye begins to lose its ability to focus on near objects. It is thought that prescribing this type of lens for a young person can change the amount of defocus on the retina and reduce the development of nearsightedness. Most studies have shown that the reduction is not enough to be very significant to most of us in the real world. This may be because bifocal or progressive lenses are limited in the amount of defocus that they can create on the retina.

Multifocal Contact Lenses

Studies show that fitting a patient with a specific multifocal contact lens can reduce the progression of nearsightedness by 50%. A multifocal contact lens attempts to deliver a significant amount of “plus” power to the eye. It seems that only “center-distance” multifocal lenses can achieve the desired effect. However, most multifocal or bifocal contact lenses on the market are “center-near” designs.

Pharmacologic Intervention

Pharmacologic intervention for reducing the progression of myopia centers around the instillation of special medicated eye drops such as low-dose atropine. Atropine was once used during eye exams to dilate the pupil and to cause the focusing muscle, the ciliary body, to become totally relaxed for measurement purposes. Atropine given at very low doses slightly relaxes the ciliary body. Studies have shown good reductions on the progression of nearsightedness even at extremely low doses. However, most doctors feel that atropine is more useful as a secondary therapy.

Orthokeratology

Orthokeratology is a method of fitting reverse-geometry contact lenses to temporarily reduce nearsightedness in the hopes that patients will eventually only need to wear “retainer” lenses at night and can enjoy glasses-free vision all day long. The lenses are called reverse-geometry lenses because instead of the curve being steeper in the center, it is flatter than the peripheral curves. This treatment has a compression and molding effect to reduce the curvature and power of the cornea. Orthokeratology is a temporary reduction in nearsightedness.

To vision scientists' surprise, these reverse-geometry lenses affect how the peripheral light rays focus. The way the retina interprets this focus causes the eye to not become more nearsighted. Eyes that have the tendency to elongate or become more nearsighted seem to stabilize and in some cases, the nearsightedness actually decreases.

What You Should Know

In the past, nearsightedness was something you either had or didn't have, and if you
had it, it was managed with corrective lenses. Vision scientists now believe they have the potential to correct or improve the underlying problem and are employing several innovative approaches to accomplish this. In the future, people with nearsightedness are likely to have many more options for treatment than they do today.

SOURCE: Caroline, Patrick and Alex Hui. Increasing prevalence of myopia underscores need for control. Primary Care Optometry News, Jan 2015.

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